BOSTON - A federal judge on Thursday threw out the death penalty sentence against a man convicted of killing three people in Massachusetts and New Hampshire during a weeklong crime spree in 2001 and ordered a new trial to determine if he will be put to death.

Chief U.S. District Judge Mark Wolf ruled that Gary Sampson was denied his constitutional right to have his sentence decided by an impartial jury and that he is "entitled to a new trial to determine whether the death penalty is justified in his case."

Sampson, a drifter who was raised in Abington, pleaded guilty to carjacking two Massachusetts men after each picked him up hitchhiking. He said he forced both men to drive to secluded spots, assured them he only wanted to steal their cars, then stabbed them repeatedly and slit their throats.

He then fled to New Hampshire, broke into a house in Meredith and strangled a third man.

In a motion for a new trial, Sampson's lawyers argued that three jurors had given inaccurate answers to questions they were asked during the jury selection process.

Wolf found that one of the jurors had intentionally and repeatedly answered questions dishonestly in an attempt to avoid talking about subjects that were painful to her. She never disclosed, for example, that her husband had a rifle and had threatened to shoot her, that she had ended her marriage because of her husband's substance abuse and that her daughter had served time in prison because of a drug problem.

Wolf said in his ruling that if the woman had disclosed those things during the jury selection process, the court would have found that there was a "high risk" that after listening to the evidence at Sampson's trial, her decision on whether to sentence Sampson to death could have been influenced by her life experiences. Wolf said the woman likely would have been excused from serving on the jury.

"In essence, despite dedicated efforts by the parties and the court to assure that the trial would be fair and the verdict final, it has now been proven that perjury by a juror resulted in a violation of Sampson's constitutional right to have the issue of whether he should live or die decided by twelve women and men who were each capable of deciding that most consequential question impartially," wrote Wolf, who presided at Sampson's trial.

Sampson was the first person sentenced to death in Massachusetts under the federal death penalty law. Massachusetts, which does not have a death penalty, has not executed anyone in more than half a century.

Sampson pleaded guilty to federal charges in the carjacking and killing of Jonathan Rizzo, a 19-year-old college student from Kingston, and Philip McCloskey, 69, of Taunton, in July 2001. A federal jury in Boston recommended the death penalty after hearing weeks of gruesome testimony about the killings.

Separately, Sampson pleaded guilty in state court in New Hampshire in the killing of Robert Whitney, 58, of Concord, a former city councilor. Sampson received a life sentence in Whitney's death.

"Gary Lee Sampson has admitted to the cold-blooded murders of Philip McCloskey, Jonathan Rizzo and Robert Whitney. Today's order does not change that fact," U.S. Attorney Carmen Ortiz said in a statement.

Ortiz said prosecutors will meet with the victims' families to discuss the ruling and plan to "examine all of our legal options." Said Christina DiIorio-Sterling, a spokeswoman for Ortiz: "We are strongly considering an appeal as one of the options."

During the trial's sentencing phase, Sampson's lawyers said he was abused as a child and suffered from bipolar disorder, damage to the frontal lobe of his brain, and drug and alcohol addiction.

Family members of the victims could not immediately be reached for comment on Wolf's ruling.

Former U.S. Attorney Michael Sullivan, who brought the case against Sampson, said he is disappointed that Sampson will get a new death penalty hearing.

"I feel horrible for the victims' families," Sullivan said.

"Sampson is an admitted cold-blooded killer and he deserves the death sentence that the jury imposed," he said.

Wolf had ordered that the execution be carried out in New Hampshire  the closest state with a death penalty  to make it more accessible to Sampson's victims. New Hampshire has a death penalty, although it hasn't executed anyone since 1939.